Watching Paint Dry, and Saying Goodbye to a Friend

Well, we're on hold with the airplane while the first coat of interior paint cures (and I've also decided to strip the paint from the stainless firewall... not sure why I didn't just mask it the first time around) so we've had some more free time than usual. That actually works out, because I've been asked to be part of a formation flight in memory of our friend Lee Naaktgeboren who sadly lost his battle with cancer over the weekend.

Lee was a friend who I'd describe as a master-of-all-trades, who had the ability to fill in any gaps at the Marion airport (C17) that might ever have arisen. If something needed to be done or improved upon, Lee just went and did it without even asking for help-- and sometimes before you even realized it needed to be done! His generosity and work ethic were both unrivaled by almost anyone, and he helped keep the airport operating smoothly all the way up until just a few days before he passed. Although I didn't get to know him quite as well as many others at the airport, he still made quite an impression on me and taught me a thing or two about more than one or two things. He will be missed by many.

The formation flight was to be a choreographed event involving several maneuvers, including a Missing Man fly-over for the final pass. I was chosen to participate in part because I fly a Piper Archer (Cherokee family), and the formation was to be a flight of Cherokees. The flight ended up being four of us, with three Cherokees and an Aztec... still a Piper I guess, but of course a much faster and more capable, twin-engined variety. This was my first experience being part of a "proper" formation flight other than the occasional goofing-off formations that tend to happen on the way to a cookout or an EAA event. In truth, all four of us tasked with this mission were a bit inexperienced at flying in formation, and we all learned quite a bit!

We did our first rehearsal Monday evening, which went fairly well but really was just a warm-up to flying with each other. Tuesday over lunch I came back out to the airport to do some solo airwork and touch & go's, trying to really get back in tune with the Archer (I had been flying a 172 lately). Then this morning we really hit it hard with practice, putting in about 3 hours of flying and as many on the ground discussing the different procedures. Tonight, it was showtime!

With about 100 (maybe more) folks in attendance at the airport, we proceeded to take off in sequence and joined up in formation on an extended downwind leg from the pattern. For our first flyover, we approached the airport from the north at a high rate of speed, and descended to a very low height before breaking off in a relatively aggressive climb and turnout in different directions. I filmed most of the action from my Garmin Virb, attached to the left rear window of our Archer:



We then rejoined in formation south of the airport and came back in for the missing man formation:



After this maneuver, we rejoined one last time on the north side to come back to the airport and do an overhead to land. It was a great experience, and I feel like one hour of flying formation like this helped me gain more experience and skill than 30 hours of cross-country solo flying. Plus, and of course more importantly, we were able to pay tribute to a great man who left us too soon. Thanks go out to the other pilots involved, in no particular order: Tim, Justin, and Cole. I was truly honored to be able to be a part of this!

Fair skies, Lee.

Section 34 Complete - Oil Cooler Mount - Interior Paint 1st Coat

Busy weekend! Started off Saturday morning attending a EAA Young Eagles event in Tipton, IA (8C4) and providing some ground help marshaling planes and escorting guests around the ramp. We had a great turnout, and it was awesome to see so many people from our chapter (#33) present. Two certified aircraft showed up-- a Mooney and a 172-- in addition to that though we had 5 experimentals including 3 Long-EZ's and 2 RV's giving rides! Very cool to watch our chapter pilots do what they do best in some gusty crosswinds at an airport that had some fairly challenging and wind-jumbling trees and terrain. Smiles all around!

After that though, it was time to get back to work and finish up the last remaining part of the baggage door: the F-1031 frame. My idea was to install a micro switch inside the frame, and put a small access cover in place of the original striker plate that would normally be there. After taking a few measurements and marking off the piece, I ended up with this:

The F-1031 Upper Baggage Door Seal Channel after installation

I don't have a pic of the cover plate or the micro switch, but the switch is attached to the cover plate and has a small steel wheel that protrudes out the back side (inboard side) of the channel. When the baggage door is closed, the latch catches on this wheel and pushes it in flush with the channel, activating the switch. This way, even if the door is fully closed, but the latch isn't latched, the switch will still indicate that the cargo door isn't properly closed. Should work pretty slick!

That puts an end to Section 34... yay! Before moving on to interior paint, I decided to assemble and install the oil cooler mount that I had custom-modified a few weeks ago to accept a larger-sized cooler. It went fairly well, although a few of the rivets along the top were fairly difficult to access. I ended up having to install just the top flange by itself to the firewall, allowing me to bend it down quite a ways to access the top row of rivets, and then assemble the rest of it as it got attached to the firewall. The resulting product looked great!

Custom oversize oil cooler mount, final installation - L side

Custom oversize oil cooler mount, final installation - R side

EDIT 11/1/2015: I think I may have messed up. Now that the finish kit is here, I see that the engine mount will actually get in the way of the larger oil cooler. I may have to redesign this mount from scratch, we'll see. Keep looking for updates on this.

The next order of business before we start bending brake and fuel lines is to paint the interior. Most parts of the interior will be carpeted or upholstered anyway, but the idea of painting the interior is to give the underlying structure a kind of consistent "base" color so that you won't see any unpainted surfaces in all the little nooks and crannies that won't be covered up. I've decided to go with a simple and inexpensive rattle-can paint, Rustoleum "Hammered" Black. The hammered pattern should give a nice look and spray on relatively easily.

I spent about an hour or so masking off all the parts I didn't want to get paint on, and in retrospect I think I should have spent even more time. More overspray got inside the tunnel and under the front seat than I had anticipated, which isn't a huge deal but it would have been better if I could have kept it brighter white. I may try and repaint it white or leave it alone, we'll see. Also, I never masked off the firewall so it ended up getting painted too. Not sure how I feel about that, we'll see how well it adheres to the stainless.

The first coat took 4 cans, and came out relatively well. It got a little blotchy in a few areas where I started to run low on paint, but I'll wait the recommended 48 hours and throw another light coat on. I imagine 2 more cans ought to do the trick. I'll also need to paint a number of other panels off the plane, so I'll probably need a total of maybe 4 more cans. Here's what it looks like so far:

Aft interior section after painting first coat

Forward interior section after painting first coat

That's it for now! We'll give this first coat 48 hours to cure and then try and shoot a light second coat over it and see if we can fill in a few of the light spots. Stay tuned for that!

Baggage Door

Got the baggage door strut installed tonight! After measuring open and closed distances, I fabricated some mounting brackets, riveted the inside door skin into place, drilled a couple holes and installed some #8 machine screws purchased in the "aviation aisle" of the local home supply store. The resulting setup looked like this:

Baggage door strut laid into position (mockup, not fastened yet)

Closed eye-to-eye distance of 5.5"

Open eye-to-eye distance 9-1/8"

The geometry came out great! To attach the strut on the airplane side, I ran a 2" long #8 machine screw down through the F-1034B/F Seat Back Braces and cut some leftover aluminum tubing to use as a spacer between the two halves. You can kind of see it in the first photo above. After temporarily installing some washers and nuts, I was able to verify the proper movement and latching of the door, which seemed to operate perfectly!

There's just one problem.

Whoever posted in the forums that they used (and recommended) a *20-lb* force gas spring is either considerably stronger than I am, or completely insane. 20 pounds doesn't seem like a heck of a lot, but rigged up in this manner, it is WAY too strong. When you pop the latch, the baggage door jumps open and basically punches you straight in the gut if you're not ready for it. If only I had the camera rolling the first time I opened the door, all proud of my work.

So, I'll be ordering a different strut from McMaster with a 5-lb force rating (#9417K6) as well as returning the bracket that I had originally ordered. The bracket was a good idea, but being relatively large and made of steel, it was way too big and bulky to really use on the baggage door. It was much easier (and cheaper) to make my own bracket out of aluminum angle.

Last order of business for the baggage door: Fit a micro-switch to the F-1031 Baggage Door Seal Channel. Hopefully we'll be able to knock that out this weekend, and finally get around to painting the interior too!

Baggage Door - EAA Tech Counselor Visit #3

One step closer to finishing the baggage door! Tonight I fabricated and installed a stiffening plate across the baggage door frame where I had cut it to fit the latch. I'm pleased to say it added the exact stiffness I was hoping it would, and now the only thing left to do is find and install a mini strut to hold the door open and prevent it from opening too far.

The stiffening plate connecting the two halves of the baggage door

As for the strut, I believe I've found the correct part for that from McMaster-Carr, P/N 9417K6, a "Miniature Gas Spring" with travel from 5.55" - 9.05" and 20lb force (edit- see later post here, recommend 5lb force instead), combined with P/N 9417K92, the accompanying mount bracket (edit- this bracket is too big and bulky, just make your own out of aluminum angle). The parts are on their way, and I'm hoping they work out nicely. After that is installed, we're just a few blind rivets away from calling the baggage door 100% complete!

In other news, our EAA Tech Counselor came by tonight for a visit to see the project. This is technically his third time here in the shop, but the first time was before we even set our first rivet on the empennage kit, just to look over our shop and tools, and to make sure we were on the right track. The second visit was after we had completed the elevators but hadn't yet started on the tailcone. Unfortunately, during those previous visits we never completed any official EAA paperwork to document the inspections (other than logging it ourselves). No big deal but in hindsight it would have been nice to have done it just to cross t's and dot i's. This time, though, we got our yellow slip:

EAA Tech Counselor Notes

He did an extremely thorough job inspecting the wings and fuselage, and I'm happy to say that overall he had some very positive feedback for us. He even noted "excellent workmanship overall" in the comments.... wahoo! Talk about how to brighten someone's day. It felt incredibly rewarding to have an expert in E-AB aircraft (and an RV-6 builder/owner himself) look over our work and give it the thumbs-up. The only thing he noticed was on the aileron torque tubes, the nuts holding the tubes to the bearings didn't have enough thread showing. The FAA rule is that there must be at least 2 threads showing beyond the nut, and on our wings that didn't work out to be the case:

The aileron torque tubes with AN365 locknut and washer, and only ~1 thread sticking out the top

I was already aware of the "2-thread" rule, but admittedly I guess I thought it was more of a guideline and not a hard-fast rule. Also, I thought I had the hardware installed per the plans, so "it must be right." Plus, the way the whole tube is in there, there's no way it's coming out even if the nut were to fall of entirely somehow. So at first it seemed like kind of a trivial finding, but since it's an FAA rule and will surely be looked at by the DAR when they come to inspect the plane for airworthiness, this could end up costing us a fair amount of time (likely several weeks) if they ding us for it and make us fix it, then we'd have to perform the fix and reschedule a time for another inspection. Way better to remedy this now!

So how did this happen in the first place? Well, we got out the plans for the wing and turned to Section 23 (aileron actuation) and reviewed the hardware callouts. Guess what? We goofed. They call for an AN364 (which is a low-profile version of the more common AN365) locknut to be installed in this location... oops!

The hardware callouts in the plans, Section 23-7, Figure 1

Simple oversight on my part in the callouts. Definitely a good catch, and lesson learned! I'll have to dig up the correct hardware (couldn't find any AN364 nuts in my hardware bins) and swap them into place, should be a very straightforward fix.

Other than that one finding, everything else went very well during the inspection! We then spent a long time discussing all kinds of things from avionics to flight characteristics, and all the different aircraft he's seen over the years. I can't possibly stress how thankful I am that a program like EAA's Tech Counselor program exists, and even more so for the individual counselors who volunteer their time to help others like us get through their build in a correct and safe manner. Thanks Tom! :-)

The Garage Got A Facelift!

Unfortunately, you probably can't even tell much is different in the photo above. But rest assured, what you're looking at is the product of 2+ weeks of cleanup, reorganization, and construction of several entirely new items-- including two 30" x 96" workbenches, two 4' x 6' shelving racks, and a lumber storage cart. Things were getting out of hand around here with respect to old projects, tools, parts, wiring, scrap wood, dust, etc etc. Quite simply put, it was time for some fall cleaning.

One of the two new workbenches

Built this lumber storage cart from a slightly simplified version of plans found in this video:

https://www.youtube.com/watch?v=nZtIEFa3Ofk

Anyway... although taking time away from building to take care of these things was a bit disappointing, it was a much-needed effort that I'm sure will pay off bigtime as we move forward!

Hopefully the next post will be on the subject of "direct" airplane construction! And hopefully soon!

We have a hangar!

Well it's been quite a little while since the last update, a lot has been going on but unfortunately very little "direct" work on the plane. I was on travel most of last week, and now this week has been filled with lots of other extracurricular events-- most of which centered around aviation though, which makes it ok, right? :-) I've also decided to do a deep-clean of the workshop before winter hits, which is likely going to continue for at least the next week or so. One bit of great news, we got our hangar lease signed tonight... woohoo!!

Our new RV-10 home at KCID!

Since we probably won't be moving the plane to the hangar until (at least) next spring, you might think this is a bit early to sign a lease and everything. Well unfortunately the way it works around here is you have to be on a waiting list (which we've been on for the better part of a year), and then when your name comes up you've gotta bite on the particular hangar that has become available or else you go back to the bottom of the list. Our name got pulled last week for this hangar while I was away, and this is one of very few "ideal" hangars that we had been hoping to get... it's one of the larger-size ones they have to offer in the price range we had, and it's insulated with electricity. So we said hey, why not, let's do it now!

Over the next few months we may move the wings out here, set up a work table or two, and hopefully install a natural gas heater (still waiting to hear back from management about that). If we can't do that we'll just use a space heater which would be fine too. Sarah is also furiously at work deciding where the sectional couch, area rug and mini-fridge will go ;-)

Other than that, we've just been cleaning and organizing in the shop, and receiving a number of packages in the mail including fuel system components, wiring, stick grips, and a bunch of other stuff. It's always fun seeing the UPS man and wondering what gifts he's bearing this time!

The next step with the plane itself will be to paint the fuselage interior, which I hope to get started on by early next week if all goes well with the garage deep-clean. Will post then with progress!

Baggage Door

Happy Labor Day! Well, this turned out to be an "interesting" 3-day holiday weekend for us. We went to Des Moines to attend our friends' wedding, but unfortunately we got our dates mixed up (100% my fault) and thought the wedding was on Saturday instead of Sunday. It turned out that there was also a different wedding taking place at the same time and location on Saturday, which we of course ended up at, all dressed up and ready for a fun night. It slowly dawned on us that we were in the wrong place when we didn't recognize anyone in attendance, including the bride and the groom once they appeared. Sometimes an epic fail makes for a great story!

Mike and Sarah at the wrong wedding... Thanks to the groomsman who took this photo!

So by the time we stayed another night in Des Moines to attend the correct wedding, we really didn't get much time to build over this long weekend. That's ok though! We did get some time to continue with the baggage door and take some more pictures of the custom latch assembly though:

Cutout is 1" x 3-3/8", starting 1/2" forward of the aft edge of the door and vertically centered on the existing hole punched for the key lock. The cutout will go through two rivet holes in the door leaving two small notches in the cutout, but they will be covered by the latch when it's installed.

A 1/8" thick steel plate 3" x 5" was fabricated to strengthen this area of the door. The cutout at the bottom is made to clear the baggage door frame.

The latch installed into the hole and screwed into place

The baggage door with latch installed

The inside baggage door cover with modified  cutout, measuring 3-1/4" x 1-1/2". A new #30 hole was drilled to mate with the frame, which must be cut to allow clearance for the latch.

The door riveted together and installed in the plane

The latch holding on to the F-1031 Upper Baggage Door Seal (the bolt is temporarily wrapped in electrical tape until I get a rubber stopper for it)

Closeup of the latch and frame cutout

The open baggage door, inside cover isn't riveted on yet

A video of the door in operation

It works great!! I still need to figure out two more things with the door before it's done: (1) The frame needs stiffening in the area where I cut it so that it won't have a tendency to bow. It's not bad as-is but I want it to be a little better. I should be able to rivet a piece of 0.032" aluminum between the two halves and that should easily take care of it though. (2) Before riveting on the inside cover, I want to source and install a small strut to facilitate the opening and closing of the door, as well as limit its travel. In addition, I'll need to finish up the F-1031 channel and install provisions for a microswitch and striker plate. Again, shouldn't be too big of a deal.

That's pretty much it for now! I'll be on travel the rest of this week, so there probably won't be much more progress until this coming weekend... until next time!

Baggage Door

As stated in an earlier post, I held off on completing the baggage door section while I searched for a latch mechanism that I could install and have a little bit more advanced open/close function than the standard lock-arm provides. Well, good news! I have found and settled on a latch: The Southco model C2-33-21.

Southco C2-33-21

This latch works by pushing in where the key lock is, and then the rest of the lever "pops" out. There's actually a video I found of its operation here on youtube: https://www.youtube.com/watch?v=h2d2S5Rcqgg. One downside is that the key for this will be different than the one for the door locks and ignition, but I think that should be ok. To close, the arm has an adjustable bolt that will catch on the back side of the F-1031 Upper Baggage Door Seal and hold the door shut tight. I'll probably have to install some kind of striker plate for that (maybe even with a microswitch) so that it's not just holding on to the aluminum. Shouldn't be too hard.

Well, I got the latch in the mail yesterday and so it's time to get to work on it. Unfortunately I don't have any pictures of the process yet (I will soon, I promise) but it's going really well so far! I was able to hang the door and get everything aligned and the hinges drilled. I'm really happy with the alignment of the door. It was a process that took a little longer than I imagined it would, and it was really quite tedious to get it to sit just perfectly centered and square in the opening, but Sarah and I prevailed. I feel like part of our success was due only to luck, but I'm not going to complain about that. Once the door was hung, I then made the rectangular cutout for the latch in the door skin and also cut a steel reinforcement plate to go behind the outer skin and provide extra support. The latch fits in place and catches on the F-1031 perfectly! I really like the geometry of it, and once I get everything finalized I'll take a bunch of pics and provide measurements, etc.

In the procurement department, big things are happening too! We ordered our stick grips from Tosten; our fuel filters, check valves and Walbro pump are on the way; ordered some 2 AWG welding cable, ring terminals, and hydraulic crimping tool from Temco; got some Amphenol 31-326-RFX BNC connectors and Harbour RG400 cable; and finally bought the necessary 5052-O tubing and a number of AN fittings from Aircraft Spruce to be able to start fabricating the fuel and brake lines. I've been talking with the folks at DJM about a console throttle quadrant for the RV-10, and I've also been talking with Paul Grimstad about the Control Approach rudder pedal system. He's working on a new design and it's taking a bit longer than I think he originally anticipated, but the good news is he is "back in business" making pedals so however long it takes it will be worth the wait! He's been great about getting back to my many pestering emails and providing updates, photos, etc. I'm confident this will NOT be a P-200 mag situation ;-)

I've also been pondering what to delete/add to my finish kit order. I've looked through a number of build blogs about this and have settled on doing pretty much the same thing Ed Kranz/Justin Twilbeck did for their finish kits as far as deleting wheels/tires/axles to upgrade to the Matco/Desser products, and a few other tidbits. Justin's delete list can be found here. I'm also going to be deleting the windows because I'll be using the Cee Bailey ones. I really hope that upgrade is worth it, I haven't bought them yet but since I've already deleted the fuse windows I'm kinda stuck with that decision now. I'm sure it will be fine.

Well, that's pretty much it for now. Hopefully for my next installment I'll get some photos up of the baggage door!

Brake/Fuel System Design - Initial Plan

<<<I apologize in advance, this is going to be a long thread filled with lots of theories, ramblings and thoughts.>>>

So tonight instead of doing any actual "work" on the plane, I did some major research and planning on the brake and fuel systems. The brake system is fairly straightforward--at least the part in Section 36--which essentially runs two lines from the firewall area to the landing gear mount area. If you want to include the Matco parking brake, then it's a simple insertion into the lines "somewhere." Most folks install their parking brake valve on the firewall, but after reading a pretty descriptive (and hilarious) description from builder Myron Nelson about how difficult it is to reach the valve should it ever need servicing, I will be locating mine at the rear of the tunnel, where the brake lines diverge to go to the R and L sides. While unconventional, this location should be a lot easier to access in the future, and make for an easy control cable run in the tunnel. Pics and diagrams to follow.

Next, on to the fuel system. By far, this is the more complex, expensive, and thought-provoking system between the two. It is also a system that has been over-engineered and/or over-complicated by more than one builder, and sadly it is has also been at least a contributing cause for a number of fatalities in the experimental aircraft world, including the infamous accident that killed John Denver. There has even been one or two accidents involving RV-10's and poor fuel system design, although both of the ones I am aware of also involved highly modified automotive engine installations, which of course kind of throws all the usual stuff out the window to begin with. That's not what we're going for here.

What we ARE going for here though is what I'm going to call a "minor variation" on a tried-and-true system design, for two very specific reasons: (1) I am installing a fuel return line for future compatibility reasons, should I decide to install an electronic fuel injection system (e.g. EFII); (2) I will have provisions to connect a removable auxiliary fuel tank in the backseat or cargo area when extra endurance is required. Nothing too crazy, but any kind of modification needs to be considered very (and I mean VERY) carefully. So, we need to start with a standard RV-10 fuel system, analyze the crap out of it, and then (did I say carefully?) make our tweaks. So... keeping all this in mind, let's get started. Here is a diagram I made of a relatively standard, tried-and-true fuel system design to start with as a reference point.

"Standard" RV-10 fuel system design, IO-540 w/ Mechanical Injection

So I'm starting with this diagram above and calling it "Standard", but really there are already a few modifications depicted here. Notably, the check valves on each of the R/L vent systems, and individual pre-filters instead of the single filter at the boost pump module. The vent check valves are installed in each wing root and serve as a secondary vent, should the primary vent become clogged with ice (or a very unlucky bee). The individual prefilters simply separate the R/L fuel tanks a bit more, so that in the event one tank coughs up some really nasty gunk in the fuel and clogs the filter, you can still switch to the other tank and have unobstructed flow. These are two very common modifications that are pretty well documented already on other builders' sites, and I feel that they are both accepted pretty openly as safety improvements for protection against icing and fuel contamination.

So now, let's analyze the system a bit and look at the individual components, particularly the boost pump module. In the diagram above, the boost pump module is shown as three individual parts above the fuel selector: The check valve, the boost pump, and the regulator (or pressure relief valve). The way it works is best understood if we split into two distinct modes of operation: boost pump off and boost pump on.

• Boost pump off: Suction from the engine's mechanical fuel pump pulls fuel through the check valve and forward through the system. Fuel can technically also flow through the pump and its internal check valve (if present) but we will consider that a path of more resistance. Fuel does not flow through the regulator.
• Boost pump on: The pump pressurizes fuel going toward the engine, "forcing" fuel through the engine's mechanical pump and increasing system pressure, particularly at the inlet side of the mechanical pump, which is where vapor lock can occasionally occur. Due to this change in pressure, the check valve closes and prevents fuel from flowing backwards. Lastly, because the boost pump is capable of producing higher than desired pressure, the regulator opens for any excess of ~30psi and allows some fuel to return to the pump inlet.

Looking at the different boost pump modules available out there, I came across three different brands: The Van's-endorsed Airflow system, the Andair system, and the EFII system.

The ironically-named Airflow fuel pump module seems to have a number of happy customers, and it is Van's choice (always a plus), but it uses an Airtex fuel pump which is a brand I have quite a bit of personal experience with in the automotive world and regard them as inferior to just about any other kind out there. Furthermore, you can go buy the Airtex E2351 fuel pump used in that module for around $60, so I'm a little hard-pressed to cough up $500 to buy it.

The Andair pump looked awesome at first glance. Less external lines and fittings to go wrong, an internal regulator, and oh wow a BRUSHLESS motor! I've always wondered why brushless fuel pump motors haven't really caught on, it seems like they would be vastly superior to the traditional brushed motors in terms of both noise and longevity. Well, it turns out after reading a number of articles online about this particular pump that it is actually *louder* than others and there have been a number of failures, particularly early on due to some early design flaws. A rather disgruntled early-adopter made a video highlighting all the design flaws of this pump and posted it to Youtube, visible here. To be fair, it appears that the company has made improvements to the design since this time, and I am not aware of any recent failures of this pump. Even so, that was enough to make me move on, especially since this is the most expensive of the three options... the FPK-540 is priced at $850!

Finally we have the EFII module. This thing seems great-- it uses a Walbro brand pump (MUCH better than the Airtex in my opinion) and it has a custom check valve/regulator that boasts the lowest "cracking pressure" of the three available models. This means that the mechanical pump doesn't have to "pull" as hard to get fuel when the boost pump is off, which is a good thing especially at high altitudes or hot temperatures. And, it's very competitively priced at $649.

Between the three choices, to me the clear winner is the EFII module. There's just one thing left to consider though: the fuel return line that I have available on my system. If we take a second look at how these boost pump modules work, we can introduce an additional benefit that a true return line can provide. The way these modules are designed (in the absence of a return line) is that the regulator's return path is cut very short, sending fuel back only a few inches and re-introducing it at the inlet of the boost pump. With low demand from the engine (e.g. on descent), the majority of fuel follows this small circular path, absorbing heat from both the pumping process and the warm environment of the tunnel. Since we want our fuel to be as cool as possible for a number of reasons, this is not an ideal situation.

So, what if we pieced our system together instead of buying a pre-made module, using exactly the same kinds of parts as above, but allowed for the regulator to send fuel all the way back to the tanks? I spent hours online tonight, searching for pumps, check valves, and regulators, and I believe I have found a winning combination:

• Walbro GSL393 fuel pump ($98.18). This is (I believe) the exact same model of pump used in the EFII boost pump setup. It has exactly the right spread of pressures and flows to exceed the demands of a 260HP IO-540 engine without going way overboard. The larger GSL392 pump is somewhat more popular in the automotive world but it has significantly higher output, which really is unnecessary here. The GSL393's performance chart can be seen here:

Walbro GSL393 Pump Performance

• McMaster-Carr 47715K21 check valve ($30.07). This valve has 0.5psi cracking pressure (VERY low) and PTFE seals that work well with all kinds of fuels and in a wide range of temperatures. I had originally considered some other valves with Buna-N (nitrile) or Viton seals, but nitrile doesn't hold up to certain kinds of fuel additives, and Viton doesn't perform well in cold temperatures (below around +10 deg F). I actually spent considerably more time than I thought I would looking at check valves, there are a lot of different options out there and care must be taken to choose the right one.
  (EDIT 9/2/15: After further research, I've selected the Parker 2625 "Swing-type" check valve, price TBD. This valve is aluminum instead of brass, and has a fluorocarbon seal with even greater temperature range, and is designed specifically for fuel systems like this)
• Aeromotive 13301 Fuel Pressure Regulator ($131.94). This regulator is adjustable between 3-65psi (30psi desired here), and will work perfectly to send excess fuel back to the tanks. It is also rebuildable and seems to have a strong history of reliability.
  (EDIT 9/2/15: A simpler method may be to use a standard relief valve with 25 or 30psi rated pressure. I'm torn between the two options and will keep searching on this.)

Cool! The same and/or equivalent parts for less than $300... I like it. So that's it, you say? Well, almost. There is one more thing to consider. Now that we have a standalone regulator, what if we move it to the head of the line and "tee" it off the entry to the fuel injection servo? This way, we eliminate any potential over-pressurization issues along the whole fuel system, and we now have the ability to run cooler fuel all the way to the servo. This should pretty much eliminate any hot-start issues and/or occurrences of vapor lock. This isn't a wild or crazy idea of mine, either... it's been the standard for how automotive fuel injection systems have worked for at least the past 30 years (which is of course about 40 years *after* these Lycosaurs were designed). So, after all that, I present you with my first draft of the fuel system diagram:

N165MJ Fuel System Design - First Draft

(EDIT: To see post with Second Draft, click here)

If you've been following along from the previous diagram, you'll see that really not much has changed except for the "duplex" fuel selector, the location of the pressure regulator, and the path of the returned fuel. I'm going to stew on this design for a little while and figure out the number of connectors, tees, fittings, etc etc that will be necessary to make this all work, and go from there. In the meantime, please feel free to comment (or email me) your ideas or opinions on this design! I welcome all feedback.

One other thing left to cover is the aux tank connections, but that is fairly simple in design. My plan there is to have two fittings and an electrical connector hidden somewhere in the R interior side wall that I will connect to a custom ~20gal fuel cell that can be placed in the rear seat floor or baggage compartment. Fuel will be burned from both main tanks as normal, and then when a tank has enough room in it to accomodate the fuel from the cell, an electric transfer pump inside the cell will be activated to refill the selected tank (either right or left) through the return line. It should work pretty slick... or at least that's the hope.

Whew! Sorry for such a long post tonight. Hopefully I've been able to document my current thoughts in a clear way. Excited to see how this all plays out!

Section 35 Complete!

Knocked off another section this weekend! By far the hardest part about this section was installing the rear floor pans, discussed in a previous post. The rest of it is really for the most part final-drilling a bunch of #19 holes, dimpling a bunch of #8 screw holes, and maybe the occasional nutplate installation. Easy peasy. Of course, this section isn't really ever "complete" until every last panel has been upholstered/painted and then screwed into position, but that's not necessarily going to happen until the plane is ready to fly-- certainly not until a number of other systems have been installed like the flight controls, brake lines, fuel lines, and wiring. So, I'm calling this section "complete" but really there's just a pile of bare aluminum panels that still need to be painted or upholstered. That will come in time!

Some of the access panels in place (shown unprimed)

It's hard to get the whole bird in the photo nowadays... not a bad problem!

Oh! I almost forgot. Spent a good amount of time this morning modifying the oil cooler mount that I had added to the fuselage kit. Because my engine has the piston cooling oil nozzles, oil cooling needs to perform better than similar engines without this feature (with the positive tradeoff of lower and more stable engine temperatures overall, of course... at least that's the theory). Due to this, I will be using a one-upsize oil cooler, the Airflow performance 2008X. This cooler is the same width and thickness as the stock one, but is about 1-5/8" longer. The mount, then, will need to be modified to accept this larger unit.

The stock VA-186 Oil Cooler Mount

Spacer brackets fabricated to extend the cooler's length

Modified VA-186 mount to accept Airflow 2008X Oil Cooler

EDIT 11/1/2015: I think I may have messed up. Now that the finish kit is here, I think the engine mount will actually be in the way of the larger oil cooler. I may have to redesign this thing from scratch, we'll see. Keep looking for updates on this.

In theory, it's not a very difficult modification. However, it ended up taking about 4 hours to get it just right. Basically, I separated the top plate of the mount from the rest of the assembly and fabricated a few spacer extensions to lengthen the open area for the cooler.. By changing the angles that the cooler originally sat at by a small degree, it retains the same footprint on the firewall and now accepts the larger oil cooler. Cool!

Speaking of cool, we've arrived at kind of a "cool" pivotal spot in the build. Most of the metalwork is done, at least as far as the primary structure of the airframe is concerned. Of course we have by no means set our last rivet, but everything from here on out is really pretty minor as far as aluminum work goes. From here onward, the majority of tasks are going to be centered around plumbing, wiring, control systems, and of course FIBERGLASS. As with many builders before us who have gotten to this stage, we've sorta procrastinated on some of the smaller glass tasks that have presented themselves along the way, and now have a stack of small bits to make as well as a couple large ones. I've heard from many builders that the canopy top and doors are some of the most time-consuming and painstaking parts of the build, and make up for a substantial portion of the total build time.

Also, it's time to start buying "stuff." Everything from wiring, stick grips, fuel lines, brake lines, the rudder pedal system, custom tidbits/upgrades, antennas, lighting, upholstery, and even the beginnings of some avionics. This is both exciting and depressing, as it is going to require careful management of monthly expenses and planning out the logistics of what needs to be bought and when. The UPS guy, if he doesn't already, is going to start to remember this house over the next few months! Who am I kidding, he's gotta already know us :-)

Over the next few days, I'll be assembling a list of things left to do before the finish kit arrives (don't worry, there is still PLENTY to do, I just need to make a list and organize/prioritize). Among the next things to do: (1) measure custom lengths for brake/fuel lines and decide if we're using flex or solid lines, probably a combo of both; (2) paint the interior; (3) continue with the baggage door after my latch arrives; and (4) begin fiberglass work.

Until the list is complete though, marathon-nights of extreme building may be replaced by marathon-nights of extreme reflection on what to do next and how to do it. The metamorphosis from builder to philosopher begins....